Liu Ching-Fang, Lu Yi-Jing, Hu Chi-Chang
Department of Chemical Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsin-Chu 30013, Taiwan.
ACS Omega. 2018 Mar 23;3(3):3429-3439. doi: 10.1021/acsomega.8b00214. eCollection 2018 Mar 31.
This work demonstrates the improved stability of zinc oxide nanorods (ZnO NRs) for the photoanode of solar water splitting under voltage biases by the addition of borate or carbonate ions in the aqueous electrolyte with suitable pH ranges. The ZnO NRs prepared by the hydrothermal method are highly active and stable at pH 10.5 in both borate and carbonate buffer solutions, where a photocurrent higher than 99% of the initial value has been preserved after 1 h polarization at 1.5 V (vs reversible hydrogen electrode) under AM 1.5G. The optimal pH ranges with a minimum morphological change of ZnO NRs for photoelectrochemical (PEC) water splitting in borate and carbonate buffer solutions are 9-13 and 10-12, respectively. The working pH range for PEC water splitting on ZnO NR photoanodes can be extended to 8.5-12.5 by the combination of borate and carbonate anions. The lifetime of ZnO NR photoanodes can be synergistically prolonged for over an order of magnitude when the electrolyte is the binary electrolyte consisting of borate and carbonate in comparison with these two anions used individually. On the basis of the experimental results, a possible mechanism for the protective behavior of ZnO in borate and carbonate solutions is proposed. These findings can be used to improve the lifetime of other high-performance ZnO-based catalysts and to understand the photocorrosive and protective behaviors of ZnO NRs in the borate and carbonate solutions.
这项工作表明，通过在具有合适pH范围的水性电解质中添加硼酸根离子或碳酸根离子，氧化锌纳米棒（ZnO NRs）用于太阳能水分解光阳极时在电压偏置下的稳定性得到了提高。通过水热法制备的ZnO NRs在pH值为10.5的硼酸和碳酸盐缓冲溶液中具有高活性和稳定性，在AM 1.5G条件下于1.5 V（相对于可逆氢电极）极化1小时后，光电流保持在初始值的99%以上。在硼酸和碳酸盐缓冲溶液中用于光电化学（PEC）水分解且ZnO NRs形态变化最小的最佳pH范围分别为9 - 13和10 - 12。通过硼酸根和碳酸根阴离子的组合，ZnO NR光阳极上PEC水分解的工作pH范围可扩展至8.5 - 12.5。与单独使用这两种阴离子相比，当电解质为硼酸根和碳酸根组成的二元电解质时，ZnO NR光阳极的寿命可协同延长一个数量级以上。基于实验结果，提出了ZnO在硼酸和碳酸盐溶液中保护行为的可能机制。这些发现可用于提高其他高性能ZnO基催化剂的寿命，并理解ZnO NRs在硼酸和碳酸盐溶液中的光腐蚀和保护行为。
